U.S. patent application number 11/011276 was filed with the patent office on 2006-06-15 for cooling apparatus and process.
Invention is credited to Philippe Fert.
Application Number | 20060123843 11/011276 |
Document ID | / |
Family ID | 35840165 |
Filed Date | 2006-06-15 |
United States Patent
Application |
20060123843 |
Kind Code |
A1 |
Fert; Philippe |
June 15, 2006 |
Cooling apparatus and process
Abstract
An integrated cooling apparatus and process which includes a
source of compressed gas; a cooling unit for cooling the compressed
gas to form cooled compressed gas by heat exchange with water
having a first purity, thereby producing a stream of cooled
compressed gas and a stream of warmed water having the first
purity; a first heat exchanger for warming a stream of water having
a second purity, the second purity being lower than the first
purity, by indirect heat exchange with a stream of water having the
first purity; and a conduit for sending cooled water having the
first purity to the cooling unit.
Inventors: |
Fert; Philippe; (Faucon,
FR) |
Correspondence
Address: |
Linda K. Russell;Suite 1800
2700 Post Oak Blvd.
Houston
TX
77056
US
|
Family ID: |
35840165 |
Appl. No.: |
11/011276 |
Filed: |
December 13, 2004 |
Current U.S.
Class: |
62/648 |
Current CPC
Class: |
F25J 2205/32 20130101;
F25J 3/04121 20130101; F25J 2240/70 20130101; F25J 3/04018
20130101; Y10S 261/11 20130101; F28C 2001/006 20130101; F25J
3/04157 20130101; F25J 2205/34 20130101 |
Class at
Publication: |
062/648 |
International
Class: |
F25J 3/00 20060101
F25J003/00; C07C 37/68 20060101 C07C037/68 |
Claims
1. An integrated cooling apparatus comprising: a) a source of
compressed gas; b) a cooling unit for cooling the compressed gas to
form cooled compressed gas by heat exchange with water having a
first purity thereby producing a stream of cooled compressed gas
and a stream of warmed water having the first purity; c) a first
heat exchanger for warming a stream of water having a second
purity, wherein the second purity is lower than the first purity,
by indirect heat exchange with a stream of water having the first
purity; and d) a conduit for sending cooled water having the first
purity to the cooling unit.
2. The apparatus of claim 1, further comprising: e) a second heat
exchanger which is a direct contact heat exchanger; f) a conduit
for sending a stream of water having the second purity to the
second heat exchanger; g) a conduit for sending at least part of at
least one stream from a cryogenic distillation unit to the second
heat exchanger so as to cool the stream of water having the second
purity; and h) a conduit for sending the cooled stream of water
having the second purity to the first heat exchanger.
3. The apparatus of claim 2, wherein the stream from the cryogenic
distillation unit is selected from the group consisting of: a)
nitrogen-rich gas; b) argon-rich gas; and c) oxygen-rich gas.
4. The apparatus of claim 1, wherein the cooling unit is a direct
contact heat exchanger.
5. The apparatus of claim 1, wherein the cooling unit is an
indirect contact heat exchanger.
6. The apparatus of claim 1, wherein the compressed gas is air and
further comprises a conduit for sending the compressed gas to the
cryogenic distillation unit as feed.
7. The apparatus of claim 1, wherein the compressed gas is a
product of the cryogenic distillation unit.
8. The apparatus of claim 2, further comprising a third heat
exchanger and a conduit for sending warmed water having the first
purity from the cooling unit to the third heat exchanger and a
conduit for sending impure water of the second purity to the third
heat exchanger.
9. A cooling process comprising: a) cooling a compressed gas to
form cooled compressed gas by heat exchange with water having a
first purity; b) warming a stream of water having a second purity,
wherein the second purity is lower than the first purity, by
indirect heat exchange in a first heat exchanger with a stream of
water having the first purity to produce cooled water having the
first purity; and c) sending at least part of the cooled water
having the first purity to the cooling unit.
10. The process of claim 9, further comprising: d) sending a stream
of water having the second purity to a second heat exchanger; e)
sending at least part of at least one stream from a cryogenic
distillation unit to the second heat exchanger so as to cool the
stream of water having the second purity; and f) sending the cooled
stream of water having the second purity to the first heat
exchanger.
11. The process of claim 9, wherein the compressed gas is air and
further comprises sending the compressed gas to the cryogenic
distillation unit as feed.
12. The process of claim 9, wherein the compressed gas is a product
of the cryogenic distillation unit.
Description
BACKGROUND
[0001] When a natural resource is available at a remote site, it is
frequently required to set up an industrial plant to treat the
natural resource without the usual infrastructures and utilities
available. In particular, when the site is close to the sea in a
desert area, it is desirable to use seawater for cooling purposes
on the site and to minimize the consumption of soft water.
[0002] The present invention allows the use of an impure source of
water for cooling purposes in an industrial plant.
[0003] Industrial plants frequently include an air separation unit.
Such plants commonly chill down cooling water by direct contact
with a waste gas from the air separation unit and then cool down a
compressed air flow by direct contact with the chilled water. This
latter direct heat exchange between chilled water and compressed
air requires a water quality which cannot be met by impure water,
such as, for instance, seawater.
[0004] The solution to the problem is to use a waste gas of the air
separation plant to chill the impure water (e.g., sea water) by
direct contact between impure water and the waste gas, and then to
exchange heat between the impure chilled water and a closed circuit
of soft water. The produced chilled soft water can then be used for
cooling the airflow by direct contact.
SUMMARY OF THE INVENTION
[0005] According to an object of the invention, there is provided a
cooling apparatus comprising a cooling unit for cooling compressed
gas to form cooled compressed gas by heat exchange with water
having a first purity, thereby producing a stream of cooled
compressed gas and a stream of warmed water having the first
purity; a first heat exchanger for warming a stream of water having
a second purity, the second purity being lower than the first
purity, by indirect heat exchange with a stream of water having the
first purity; and a conduit for sending cooled water having the
first purity to the cooling unit.
[0006] The water of the first purity contains a smaller molar
percentage of a given impurity (such as salt) than the water of the
second purity. In particular, the water of the first purity may be
soft water and the water of the second purity may be impure water,
such as seawater.
[0007] According to another object of the invention, there is
provided a cooling process comprising cooling a compressed gas to
form cooled compressed gas by heat exchange with water having a
first purity; warming a stream of water having a second purity, the
second purity being lower than the first purity, by indirect heat
exchange in a first heat exchanger with a stream of water having
the first purity to produced cooled water having the first purity;
and sending at least part of the cooled water having the first
purity to the cooling unit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] For a further understanding of the nature and objects for
the present invention, reference should be made to the following
detailed description, taken in conjunction with the accompanying
drawings, in which like elements are given the same or analogous
reference numbers and wherein:
[0009] FIG. 1 illustrates an example of an integrated cooling
apparatus according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0010] The invention provides a cooling apparatus comprising a
cooling unit for cooling compressed gas to form cooled compressed
gas by heat exchange with water having a first purity, thereby
producing a stream of cooled compressed gas and a stream of warmed
water having the first purity; a first heat exchanger for warming a
stream of water having a second purity, the second purity being
lower than the first purity, by indirect heat exchange with a
stream of water having the first purity; and a conduit for sending
cooled water having the first purity to the cooling unit.
[0011] The water of the first purity contains a smaller molar
percentage of a given impurity (such as salt) than the water of the
second purity. In particular, the water of the first purity may be
soft water and the water of the second purity may be impure water,
such as seawater.
[0012] The apparatus may comprise a second heat exchanger which is
a direct contact heat exchanger; a conduit for sending a stream of
water having the second purity to the second heat exchanger; a
conduit for sending at least part of at least one stream from a
cryogenic distillation unit to the second heat exchanger so as to
cool the stream of water having the second purity; and a conduit
for sending the cooled stream of water having the second purity to
the first heat exchanger.
[0013] The cooling unit may be an indirect contact or a direct
contact heat exchanger.
[0014] The stream from the cryogenic distillation unit is
preferably selected from the group consisting of nitrogen-rich gas,
argon-rich gas, and oxygen-rich gas.
[0015] If the compressed gas is air, the apparatus comprises a
conduit for sending the compressed gas to the cryogenic
distillation unit as feed.
[0016] The compressed gas may be a product of the cryogenic
distillation unit.
[0017] Additionally, the invention provides a cooling process
comprising cooling a compressed gas to form cooled compressed gas
by heat exchange with water having a first purity; warming a stream
of water having a second purity, the second purity being lower than
the first purity, by indirect heat exchange in a first heat
exchanger with a stream of water having the first purity to
produced cooled water having the first purity; and sending at least
part of the cooled water having the first purity to the cooling
unit.
[0018] The process may comprise sending a stream of water having
the second purity to a second heat exchanger, sending at least part
of at least one stream from a cryogenic distillation unit to the
second heat exchanger so as to cool the stream of water having the
second purity, and sending the cooled stream of water having the
second purity to the first heat exchanger.
[0019] The compressed gas may be air and the process may comprise
sending the compressed gas to the front end purification and then
to the cryogenic distillation unit as feed.
[0020] The compressed gas may be a product of the cryogenic
distillation unit.
[0021] Referring to FIG. 1, a cryogenic air separation unit 17 is
located in proximity to a source 3 of impure water, such as a lake
or the sea. The impure water 1 is pumped from the basin 4 of the
main wet cooling tower 6 and a fraction of this water 9 is sent to
the top of a direct contact tower 5 in which the impure water flow
is chilled by direct contact with a waste dry gas 7. The waste dry
gas is preferably nitrogen-rich gas 7 from the cryogenic air
separation unit 17. The nitrogen-rich gas 7 is at a temperature
between 5 and 40.degree. C. and completely dry, and thereby chills
the impure water 9 by production of the latent heat of evaporation
to form chilled impure water. The temperature required for the
nitrogen-rich gas is typically that at which the gas is removed
from the warm end of a main heat exchanger of the air separation
unit 17. The flow of impure water 9 is controlled by a valve V1
that is controlled by an LIC that detects the liquid level at the
base of the tower 5. The impure water 9 is pumped to a heat
exchanger 11 where it exchanges heat with a stream of pure water 13
to form chilled pure water.
[0022] The stream of pure water 13 is sent to the top of a further
direct contact cooling tower 15 which is used to cool an air stream
19 from the main air compressor 20 of the air separation unit 17 or
of another air separation unit. The pure water 13 is sent to a
point below the demister 14 and a valve V2 controls the flow. The
cooled air 21 emerging from the top of the further cooling tower 15
is sent to a purification unit (not shown), cooled, and then sent
to the columns of the cryogenic air separation unit 17. The air
separation unit 17 produces oxygen 18 and possibly argon for use on
the site, for example, in a gas-to-liquid conversion unit or other
similar process consuming very large amounts of oxygen.
[0023] A further fraction of the impure water 23 is sent to
exchanger 25 where it cools pure water stream 27 coming from the
further cooling tower 15.
[0024] Downstream of heat exchanger 11, the impure water 9 is mixed
with the impure water 23 warmed in exchanger 25 to form stream 26.
Stream 26 is then sent back to the wet cooling tower 6 where it is
cooled by direct contact with an ambient air flow induced or fan
forced evaporation. The cooled impure water falling into basin 4 is
then recycled to the system.
[0025] The pure water 27 is pumped by pump 29 and divided into
three streams. Stream 13 is sent to exchanger 11, stream 31 is sent
to an intermediate level of the further cooling tower 15 via valve
V4 at a higher temperature than that at which stream 13 enters the
cooling tower 15 as cooled water, and stream 33 is sent to other
pure water consumers, for example, cooling circuits on the site
(e.g., compressor intercoolers). Warmed stream 33 is then mixed
with the rest of the water from the bottom of the cooling tower 15
to form stream 27.
[0026] It will be noted that cooling tower 15, which is a direct
contact heat exchanger, could be replaced by an indirect contact
heat exchanger.
[0027] It will be appreciated that the gas 19 cooled in further
cooling tower 15 could be any gas requiring cooling.
[0028] The pure water volume in the circuit increases since
humidity present in compressed air stream 19 is condensed in
cooling tower 15. This water contains no dissolved minerals and is
slightly acidic due to the carbonic acid produced by the carbon
dioxide present in the air. It is generally not necessary to
neutralize this water to avoid corrosion. However, it may be useful
to inject soda to control the pH. The water level in the further
cooling tower 15 is controlled using a purge 35 whose volume
corresponds to the volume of water condensed in the tower. Extra
water from condensed water in air must be removed at least from
time to time. This purged water 35 can be injected into the impure
water circuit (dashed lines) or can be used as a source of
relatively pure water for another application. The flow of purged
water is controlled by a valve V3 that is controlled by an LIC
which monitors the liquid level at the bottom of tower 15.
[0029] A blow down purge 37 is used to maintain the impure water
concentration within acceptable range so the salt concentration
does not increase overduly.
[0030] Impure water 40 is added through valve V5 controlled by the
level in the basin 4 via an LIC at least from time to time to
compensate for the water lost via purge 37 and the evaporation and
drift losses.
[0031] The compressor 20 of the air separation 17 is commonly
driven by a steam turbine 43. The stream turbine condenser 45 may
be cooled using part 47 of the impure water and the warmed impure
water 47 is then sent back to the wet cooling tower 6. It will be
appreciated that the steam turbine need not be present since the
compressor 20 could be driven by other means.
[0032] It will be seen that the apparatus does not consume any
water apart from impure water 40. Since the only water in contact
with the gas to be cooled is pure, there is no risk of
contaminating the gas.
[0033] The volume of the pure water circuit is reduced and there is
consequently no risk of flooding the cooling tower or of water
drifting toward sensitive downstream equipment such as the
front-end purification unit of the air separation unit 17.
[0034] It will be appreciated that while one embodiment of the
invention has been shown and described hereinabove, many
modifications may be made by the person skilled in the art without
departing from the spirit and scope of this invention.
* * * * *